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Disorders Techniques in Investigation and Diagnosis - part 4

Lý tưởng nhất là, thuật ngữ "phì đại của các móng tay nên được giới hạn với điều kiện gây ra móng tay mở rộng và dày lên do tác động của chúng ma trận móng tay (không bao gồm giường móng tay và hyponychium). Tăng sừng subungual 'liên quan đến những thực thể dẫn đến dày | Nail plate and soft tissue abnormalities 97 HYPERTROPHIC NAIL AND SUBUNGUAL HYPERKERATOSIS Ideally the term hypertrophy of the nail plate should be restricted to conditions causing nail enlargement and thickening by their effects on the nail matrix excluding nail bed and hyponychium . The term subungual hyperkeratosis should relate to those entities leading to thickening beneath the preformed nail plate that is thickening of the nail bed or hyponychium Figure 4.13 . In practice this differentiation is difficult to define and mixed cases are commonly seen for example in psoriasis Figures 4.14 4.15 . The normal thickness of finger nails is approximately 0.5 mm this is consistently increased in manual workers and in many Figure 4.13 Cryptogenic hyperkeratosis. disease states such as congenital ichthyoses Darier s disease psoriasis and repeated trauma. The latter particularly relates to toe nails where microtrauma and footwear are constantly affecting the nails. Onychogryphosis Figures 4.16-4.18 a condition mainly seen in the great toe nails of elderly and infirm individuals is probably due to trauma footwear pressure neglect and sometimes associated poor peripheral circulation and fungal infection these and less common causes are listed in Table 4.3. A text atlas of nail disorders 98 If the nail bed is left continuously exposed by nail removal or disease for more than a few months irregular hyperketosis and failure of nail plate adhesion may ensue Figure 4.14 Subungual hyperkeratosis due to psoriasis. Figure 4.15 Distal subungual hyperkeratosis in psoriasis note proximal inflammatory brown margin. Nail plate and soft tissue abnormalities 99 Figure 4.16 Oyster-like onychogryphosis. Figure 4.17 Onychogryphosis ram s horn deformity. Epithelial hyperplasia of the subungual tissues results from repeated trauma and exudative skin diseases and may occur with any chronic inflam-matory condition involving this area. It is especially common in psoriasis pityriasis rubra pilaris